Structural, functional, and physiological signals in ichthyosaur vertebral centrum microanatomy and histology
Structural, functional, and physiological signals in ichthyosaur vertebral centrum microanatomy and histology
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DOI：
10.5252/geodiversitas2018v40a7
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发表时间：
2018-04-12
期刊：
影响因子：
1.8
通讯作者：
Sander, P. Martin
中科院分区：
文献类型：
--
作者：
Houssaye, Alexandra;Nakajima, Yasuhisa;Sander, P. Martin
第一个金枪鱼形的鱼形动物是在鱼龙中进化出来的，但事实上，这一群体在形态和游泳方式上表现出了广泛的多样性。从最基本的到高度衍生的鱼龙分类群的多样性脊椎中央的组织学和显微解剖学特征进行了分析，说明这种变化。不寻常的平行纤维骨与真正的平行纤维骨镀层的发生证实了所有这些分类群的高生长率。鱼龙的椎骨是深双凹的，显示出有限的骨内膜区域，与有限的长度增长有关。未发生骨量增加或减少。椎体呈海绵状，在骨膜区域观察到两种微型，具有不同程度的小梁网组织。的microtypes似乎是与椎体的形状，组织的海绵体成为均匀的圆椎和新鱼龙类的盘形中心，而不是更异质的线轴形的原始三叠纪形式的中心。与先前在其他类人猿中所提出的相反，显微解剖组织的主要开关似乎与深双凹盘状椎体的获得相关，而不是与游泳模式从长而细长的身体的鳗形游泳者到Thunniform游泳者的转变相关。
The first tuna-shaped amniotes evolved among ichthyosaurs, but this group exhibits in fact a wide diversity of morphologies and swimming modes. The histology and microanatomical features of vertebral centra of a diversity of ichthyosaur taxa from most basal to highly derived illustrating this variability were analyzed. The occurrence of unusual parallel fibered bone with platings of true parallel-fibered bone confirms high growth rate in all these taxa. Ichthyosaur vertebrae, which are deeply amphicoelous, show a limited endosteal territory associated with a limited growth in length. No bone mass increase nor decrease occurs. The vertebral centrum is spongious, and two microtypes are observed in the periosteal territory, with different degrees of organization of the trabecular network. The microtypes appear to be associated with the shape of the vertebral centrum, the organization of the spongiosa becoming homogeneous in the disk-shaped centra of cymbospondylids and Neoichthyosauria, rather than much more heterogeneous in spool-shaped centra of primitive Triassic forms. As opposed to what was previously suggested in other amniotes, the main switch in microanatomical organization appears thus to be correlated to the acquisition of deeply amphicoelous disk-like vertebral centra rather than to a shift in swimming mode from long and slender-bodied anguilliform swimmers to thunniform swimmers.